Electrosurgery is a common procedure for dentists, doctors, and veternarians. Electrosurgical unipolar handpieces are commercially available that will accommodate a wide variety of electrode shapes and sizes, such as needles, blades, scalpels, balls and wire loops. The conventional unipolar handpiece, such as that available from Ellman International, Inc. of Hewlett, N.Y., comprises an elongated electrically-insulating handle with a central bore and having at a first end an externally threaded part for threadingly engaging an internal thread on an electrically-insulating nose piece also fitted with a central bore. A generally cylindrical metal collet seats in the handle bore at the first end and a collet front portion projects forward from the handle. The collet comprises at its front portion flexible jaws formed by a tapered slitted front with a bore sized to receive the shaft or shank of a conventional electrosurgical electrode, and the nose piece has on its interior a matching tapered portion configured such that, when the nose piece is rotated clockwise (CW) while threadingly engaged to the handle, its tapered interior surface engages and gradually closes down the collet jaws so that the electrode, when inserted into the collet bore, is tightly held by the metal collet and a good electrical connection is made to the collet. The back end of the collet is connected to a wire which connects to a conventional electrosurgical instrument supplying electrosurgical currents which, when activated, via a switch on the handpiece or a foot switch or a switch on the instrument, supplies electrosurgical currents to the collet and via the collet to the electrosurgical electrode. When the dentist or doctor desires to change the shape, size or length of the electrode, it is necessary to loosen the nose piece to unlock the collet, remove the existing electrode, and substitute a new electrode.
Reference is made to commonly owned U.S. Pat. No. 5,630,812 which describes a handpiece of the type described above provided with a built-in structure which locks the nosepiece to the handle preventing accidental detachment, the contents of which are herein incorporated by reference.
These types of known handpieces can cause certain difficulties. These difficulties include that the collet can only accommodate a single sized electrode shank. However, the most common electrodes come in two standard-sized shanks, 1/16 or 3/32 inches. Hence, when the surgeon desires to change electrodes, and the new electrode has a different sized shank from the previous electrode, the surgeon must remove the nosepiece during the procedure, remove the collet for the previous electrode and replace with a new collet that can accommodate the shank of the new electrode. This is cumbersome and time consuming, and has the further disadvantage in that it involves a certain effort to remove the nosepiece from the handpiece when the nosepiece makes use of the locking feature described and claimed in the referenced patent.
Another disadvantage of the known handpieces derive from their fabrication or assembly procedure during manufacture of the handpiece. The metal collet, typically of brass so as to be electrically conductive, must be fixed to the handle, typically of an insulating plastic such as Delrin, so that it does not turn or move during the surgical procedure. This is currently accomplished by gluing the back end of the collet, after the electrical cable has been soldered to it, into the bore at the front end of the handle. The gluing step, which takes at least several hours due to the dissimilar materials, requires that the glued parts remain immobile while the glue dries and permanently sets. This significantly slows the assembly procedure and increases the manufacturing cost.